I need to send out notifications from my web-app and I've setup postfix as a null client on my server. So in my
/etc/postfix/master.cf I have commented out the lines
#smtp inet n - - - - smtpd #local unix - n n - - local
So after I did that when I try to use telnet, it blocks me out.
$ telnet localhost 25 Trying 127.0.0.1... telnet: Unable to connect to remote host: Connection refused
And when I use sendmail I am able to send emails, which is what I want. So far so good.
Now, I'm concerned about spammers not using my SMTP server as an open relay. To this end, do I need to turn on TLS and SMTP Auth support in postfix or is just disabling network access to postfix (by commenting out those two lines in master.cf) sufficient?
In other words, in my current setup - with TLS turned OFF and network access to postfix disabled - is there a possibility of my SMTP server being compromised?